Brian
I did a whole bunch of this in my basement and I’ll shoot some pictures. One is above. But originally I ordered it milled and the milled wood does have relief cuts. But then I ran out and had some rough stock that I milled without and I didn’t notice any difference. Also I made the T&G two different ways — originally on the router table and then later on the table saw. Both worked ok
i didn’t have issues hiding the nails. I installed with the mortise pointing down. You do though need to be careful when you nail through the tongue at the top that you do not obstruct the space behind where the next board rests.
also I just drew a line over every stud and put 1 16 gauge nail per every stud.
I just ordered some more and went ahead and ordered it milled vs me mill it. Just saved a lot of time and labor.
BTW all mine is cypress
Bob C
Thank you pinterest for giving us a shiplap shortage. Seriously, I had some on order for a month, finally gave up and made it. I would use a shaper instead of the dado because you want a flat cut. I do not back cut it, if your stock is stabil, it gains nothing. Don't overthink it, a 15g nail on an angle is tremendously strong. We do a lot of this, never with plywood backer. Two reasons, first it's unnecessary, second it breaks the fire wall. If you just put plywood to the studs, you have to drywall over it anyhow by code. You gain nothing by adding a sheet of plywood under drywall except in the rare occurrence that they may hang something heavy on it. People do these walls to show them off, not hang junk on, so don't over think it. It's not hard to hang a TV mount in a stud. You don't need to though, shiplap nailed up will hold my 260 pounds. I've tested. Glue it to the drywall if it worries you.
Brian:
here's a few more pictures. i took a couple of the milled wood that i received and also the spec for how they machined it (and pricing in case it helps).
2021-06-12 20.10.36.jpg2021-06-12 20.10.43.jpgspec.jpg
Bob C
Brian, I owe you an apology. The ash I was remembering was one of the heat modified ones like Thermory or some such brand: Much more brittle than just regular KD stuff. It sounds like you have a solid plan in place for the process. Please share pics when it’s done.
E.
Ex-SCM and Felder rep